LED apparatus with integrated power supply and a method of employing same

ABSTRACT

A Light-Emitting Diode (LED) apparatus has a power source outputting a source DC power at a source DC voltage, a plurality of LEDs drivable at a driving DC voltage lower than the source DC voltage, and an electrical path connecting the power source to each LED for powering the LED by the power source. Each electrical path comprises a first portion connected to the power source at the source DC voltage and a second portion connected to the LED at the driving DC voltage, and the length of the first portion is longer than that of the second portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/496,406, with a Filing or 371(c) Date of Sep. 20, 2019, which is anational phase application of PCT Patent Application Serial No.PCT/CA2018/050346 filed Mar. 22, 2018, and claims the benefit of U.S.Provisional Patent Application Ser. No. 62/475,049 filed Mar. 22, 2017,the content of which is incorporated herein by reference in itsentirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to Light-Emitting Diode (LED) apparatusesand systems, and in particular to a LED apparatus and system with powersupply, and methods of controlling and powering the LEDs thereof.

BACKGROUND

Light-Emitting Diodes (LEDs) are known and have been widely used inindustries, mostly as low-power light indicators. In recent years, LEDswith increased power output or increased luminous intensity have beendeveloped and used for illumination. LED lights provide improved energyefficiency, safety, and reliability, and are replacing other types oflights in the market such as incandescent lights, Compact FluorescentLamps (CFLs), and the like. As everyday lighting significantlycontributes to the burden on power grids and greatly increases theoverall requirements for electricity generation, the energy efficiencyof LEDs will play a crucial role in future energy savings. It is likelythat LEDs will dominate the lighting markets because of their superiorenergy efficiency.

LEDs with increased power output or increased luminous intensity havealso been used for image/video displays such as digital signage and thelike. Digital LED signage is a fast-growing industry due to theincreasing demand for marketing, advertising, and the like.

Prior-art digital LED signage displays utilize separate power conversionunits along with LED drivers to provide electrical power to the LEDsfrom an external power source such as a power grid. While external powersources usually output alternate-current (AC) power, LEDs generallyrequire direct-current (DC) power. Consequently, the power conversionunit of a digital LED signage requires both an AC-to-DC (AC/DC)converter and a DC-to-DC (DC/DC) converter to convert the AC input powerfrom the external power source into DC power suitable for LEDs. Suchconverters, however, are usually bulky and heavy. Moreover, they usuallyproduce significant amounts of heat and thus need suitable cooling meanssuch as fans or large heat-sinks for heat dissipation. A well-designedthermal management system is essential to a power conversion unit forLEDs.

FIG. 1 shows an example of a prior-art LED signage display 10. As shown,the LED signage display 10 comprises one or more LED display modules 12having a plurality of LEDs for display, and a cabinet 14 foraccommodating various electrical components of the LED signage display10 such a power converter, a central controller, and the like. The LEDdisplay modules 12 are connected to the electrical components in thecabinet 14 via one or more cables (not shown). In this example, the LEDdisplay module 12 is physically coupled to the cabinet 14. However,those skilled in the art will appreciate that, in some prior-art LEDsignage displays 10, the LED display modules 12 may be physicallyseparated from the cabinet 14.

FIG. 2A is a schematic diagram of the commonly available LED signage 10.As shown, the LED display module 12 of the LED signage 10 iselectrically connected to a power converter 18 and a central controller20 in the cabinet 14 via one or more cables 16A and 16B. In other words,the power converter 18 and a central controller 20 are physicallyseparated from the LED display module 12 and are electrically connectedthereto via the cables 16A and 16B.

The LED display module 12 comprises one or more LED drivers 22 driving aplurality of LEDs 24 which are usually arranged in a matrix form havingone or more rows and one or more columns. Each LED 24 may be asingle-color LED that only emits a single-color light such as a red,green, or blue light, or a multi-color LED such as a tri-color LED thatcan selectively emit multiple colored lights such as red, green, andblue lights. If single-color LEDs are used, the single-color LEDs may begrouped into one or more LED sets with each LED set comprising a red,green, and blue LEDs arranged in close proximity with each other,thereby forming a pixel of the LED display module 12. On the other hand,if tri-color LEDs are used, each tri-color LED forms a pixel of the LEDdisplay module 12.

The LED drivers 22 receive electrical power from the power converter 18via one or more power wires or cables 16A for powering the LEDs 24. TheLED drivers 22 also receive control signals from the central controller20 via one or more signal wires or cables 16B for regulating the powerdelivered to the LEDs 24, thereby controlling the lighting of each LED24 (for example, off, on, lighting intensity, color, and/or the like)for controlling the display of the LED signage 10. Depending on thedriving capacity of the LED drivers 22, each LED driver 22 may beelectrically connected to and may regulate a subset of the LEDs 24 forexample 4, 8, or 16 LEDs 24.

As described before, the power converter 18 is located in the cabinet14, and is physically separated from the LED display module 14 butelectrically connected thereto via the electrical cables 16A and 16B.The power converter 18 comprises an AC/DC converter 26 and a DC/DCconverter 28. The AC/DC converter 26 converts the AC electrical powerfrom an external power source 30 into high-voltage DC power and outputsthe converted high-voltage DC power to the DC/DC converter 28. The DC/DCconverter 28 converts the high-voltage DC power received from the AC/DCconverter 26 into low-voltage DC power (for example, at about 5V, 7.5V,or the like) suitable for powering the LEDs 24 in the LED display module12, and outputs the low-voltage DC power to the LED display module 12via the cable 16A. Therefore, existing LED signage displays 10 have alow-voltage power distribution (for example, 5V) to their LED displaymodules 12.

As described above, each LED driver 22 is electrically connected to thecentral controller 20 via the cable 16B. The central controller 20 isfunctionally connected to one or more computing devices 32 such as adesktop computer, a laptop computer, a smartphone, a tablet, a personaldigital assistant (PDA), and the like, via suitable wired or wirelessconnection for receiving instructions therefrom. In response to thereceived instructions, the central controller 20 sends control signalsto the LED drivers 22 to regulates the power delivered to the LEDs 24 ofthe LED display module 12, thereby controlling the lighting (forexample, off, on, the lighting intensity, color, and the like) of eachLED 24 thereof for controlling the display of the LED signage 10.

FIG. 2B is a circuit diagram showing an LED driver 22 driving aplurality of LEDs 24 in the LED display module 12. For ease ofillustration, FIG. 2B only shows three LEDs 24 emitting red, green, andblue lights, respectively, and forming a pixel of the LED display module12.

As shown, each LED 24 is electrically connected in series to a resisterR and a switch 34 such as a semiconductor switch and, for example, ametal-oxide semiconductor field-effect transistor (MOSFET) switch. TheLED driver 22 receives control signals from the central controller (notshown in FIG. 2B) via a wired data bus 38, and individually controlseach switch 34 via an electrical wire 40 to: (i) turn the respective LED24 on and off, and (ii) control the luminous intensity thereof.

The LED driver 22 uses a Pulse-Width Modulation (PWM) scheme to turn therespective switch 34 on and off at a sufficiently high frequency forcontrolling the electrical current flowing through each LED 24. Inparticular, the LED driver 22 adjusts the duty cycle of the pulse-widthmodulated current to control the luminous intensity of each LED 24thereby controlling the luminous intensity thereof. By increasing theduration of the duty cycle, the duration of time that the switch 34 isturned on is increased and thus the current flowing therethrough becomeslarger, thereby making the LED 24 brighter. By controlling the luminousintensity of the light emitted from each of the red, green, and blue LED24 in a pixel in response to a set of control signals sent to the LEDdriver 22 via the data bus 38, the color of the pixel may be dynamicallyadjusted for displaying an image on the LED display module 12. FIG. 2Cshows a prior-art LED driver 22 disclosed in U.S. Pat. No. 6,586,890 toMin, et al.

There are several challenges and difficulties associated with theprior-art digital LED signage displays. For example, due to the factthat a low DC voltage is distributed from the power converter 18 to theLED display module 12, the electrical current in the power cable 16A(see FIG. 2A) and in other wiring of the LED signage display 10 issignificantly large (as the power consumption of the LED signage display10 is constant), thereby causing substantial amounts of energy losses inthe form of heat. Therefore, a prior-art digital LED signage displayusually requires multiple fans and/or large heat-sinks for heatdissipation, and consequently requires an effective thermal managementsystem. The large amount of generated heat is also a risk to safety andreliable operation of digital LED signage displays.

Moreover, using fans or rotational parts for the digital LED signagedisplay significantly reduces its reliability since the rotational partsare usually the points of failure in these products.

As each LED driver 22 is connected to the central controller 20 via thecable 16B (for example, a ribbon cable), a large digital LED signagedisplay 10 generally requires one or more ribbon cables 16B having alarge number of wires therein, which makes the digital LED signagedisplay 10 expensive and unreliable since there is a high risk that thewires in ribbon cables may get disconnected and/or damaged over time,particularly in outdoor applications.

In addition, prior-art LED drivers are not able to smoothly modulate thecurrent flowing through the LEDs thereby decreasing the quality ofimages displayed on the LED signage during color transitions.

SUMMARY

Herein, a Light-Emitting Diode (LED) apparatus is disclosed. The LEDapparatus comprises a direct-current (DC) power supply outputting DCpower at a first voltage, and an LED module physically separated fromthe DC power supply and electrically connected to thereto via one ormore cables for receiving DC power output therefrom. The LED modulecomprises a plurality of LED submodules. Each LED submodule comprisesand integrates therein (i) one or more LEDs and (ii) a DC/DC converterelectrically connected to the DC power supply via the one or more cableand connected to the one or more LEDs in the LED submodule. The DC/DCconverter converts the DC power output from the DC power supply to a DCpower at a second voltage lower than the first voltage, and individuallyoutputs the DC power at a second voltage (for example, via an individualpower wire) to each of the one or more LEDs in the submodule.

In some embodiments, each LED submodule also comprises a wirelesscommunication unit for receiving control signals, and a control unit forcontrolling the LEDs via the DC/DC converter, based on the controlsignals received by the wireless communication unit.

According to one aspect of this disclosure, there is provided a LEDapparatus. The LED apparatus comprises: a power source outputting asource direct-current (DC) power at a source DC voltage; and an LEDmodule physically separated from the power source and comprising one ormore LED submodules, each LED submodule comprising therein a DC-to-DC(DC/DC) converter electrically coupled to a plurality of LEDs drivableby a driving DC power at a driving DC voltage lower than the source DCvoltage. The DC/DC converter of each LED submodule is also electricallycoupled to the power source via one or more cables and is configured forconverting the source DC power to the driving DC power at the driving DCvoltage for driving the plurality of LEDs of the LED submodule.

In some embodiments, the source DC voltage is higher than 12V.

In some embodiments, the source DC voltage is about 48V.

In some embodiments, the DC/DC converter in each LED submoduleindividually outputs the driving DC power to each of the plurality ofLEDs in the LED submodule.

In some embodiments, the LED apparatus further comprises a gateway forwirelessly communicating with a computing device. Each LED submodulefurther comprises a wireless communication unit configured for wirelesscommunicating with the gateway. The gateway is configured for wirelesslyreceiving from the computing device a command for controlling the LEDapparatus and in response, wirelessly communicating with the wirelesscommunication unit of each LED submodule for controlling the lighting ofthe plurality of LEDs in the LED submodule.

In some embodiments, each LED submodule further comprises a control unitin signal communication with the wireless communication unit and isconfigured for controlling the lighting of the plurality of LEDs in theLED submodule.

In some embodiments, the control unit in each LED submodule isconfigured for individually controlling the lighting of each of theplurality of LEDs in the LED submodule.

In some embodiments, the power source may comprise at least analternate-current (AC) to alternate-current (AC/DC) converterelectrically connectable to an AC power source.

In some embodiments, the power source may comprise at least acombination of a solar panel and an energy storage unit.

In some embodiments, the power source is switchable between at least anAC/DC converter electrically connectable to an AC power source and acombination of a solar panel and an energy storage unit.

According to one aspect of this disclosure, there is provided a LEDapparatus. The LED apparatus comprises: a power source outputting asource DC power at a source DC voltage; a plurality of LEDs drivable ata driving DC voltage lower than the source DC voltage; and an electricalpath connecting the power source to each LED for powering the LED by thepower source. Each electrical path comprises a first portion connectedto the power source at the source DC voltage and a second portionconnected to the LED at the driving DC voltage, wherein the length ofthe first portion is longer than that of the second portion.

In some embodiments, the source voltage is higher than 12V.

In some embodiments, the source voltage is about 48V.

In some embodiments, the LED apparatus further comprises: one or moreDC/DC convertors coupled to the electrical paths between the major andminor portions thereof for converting the source DC voltage to thedriving DC voltage.

In some embodiments, each LED is individually powered by an output ofthe one or more DC/DC convertors.

In some embodiments, the LED apparatus further comprises: a gateway forwirelessly communicating with a computing device; and one or morewireless communication units coupled to the plurality of LEDs andconfigured for wireless communicating with the gateway. The gateway isconfigured for wirelessly receiving from the computing device a commandfor controlling the LED apparatus and in response, wirelesslycommunicating with the one or more wireless communication units forcontrolling the lighting of the plurality of LEDs.

In some embodiments, the one or more wireless communication units arecoupled to the plurality of LEDs through one or more control units; andthe one or more control units are configured for controlling thelighting of the plurality of LEDs in response to the signal receivedfrom the one or more wireless communication units.

In some embodiments, the LED apparatus further comprises: one or morecontrol units in signal communication with the one or more wirelesscommunication units and configured for individually controlling thelighting of each of the plurality of LEDs.

In some embodiments, the power source comprises at least analternate-current (AC) to alternate-current (AC/DC) converterelectrically connectable to an AC power source.

In some embodiments, the power source comprises at least a combinationof a solar panel and an energy storage unit.

In some embodiments, the power source is switchable between at least anAC/DC converter electrically connectable to an AC power source and acombination of a solar panel and an energy storage unit.

According to one aspect of this disclosure, there is provided a methodof powering an LED module comprising a plurality of LEDs drivable at adriving DC voltage. The method comprises: providing a power sourceoutputting a source DC power at a source DC voltage higher than thedriving DC voltage; and establishing a plurality of electrical paths,each electrical path connecting the power source to one of the pluralityof LEDs for powering the LED by the power source. Each electrical pathcomprises a major portion connected to the power source at the source DCvoltage and a minor portion connected to the LED at the driving DCvoltage.

In some embodiments, the source voltage is higher than 12V.

In some embodiments, the source voltage is about 48V.

In some embodiments, said establishing the plurality of electrical pathscomprises: converting the source DC voltage to the driving DC voltage atlocations between the major and minor portions of the plurality ofelectrical paths by using one or more DC/DC convertors.

In some embodiments, said establishing the plurality of electrical pathsfurther comprises: individually powering each LED by an output of theone or more DC/DC convertors.

In some embodiments, the method further comprises: wirelessly commandingthe plurality of LEDs for controlling the lighting of the plurality ofLEDs.

In some embodiments, said wirelessly commanding the plurality of LEDscomprises: wirelessly commanding one or more wireless communicationunits to send control signals to the plurality of LEDs through one ormore control units for controlling the lighting of the plurality ofLEDs.

In some embodiments, said wirelessly commanding the plurality of LEDsfurther comprises: individually controlling the lighting of each of theplurality of LEDs in response to said commanding.

In some embodiments, the power source comprises at least analternate-current (AC) to alternate-current (AC/DC) converterelectrically connectable to an AC power source.

In some embodiments, the power source comprises at least a combinationof a solar panel and an energy storage unit.

In some embodiments, the power source is switchable between at least anAC/DC converter electrically connectable to an AC power source and acombination of a solar panel and an energy storage unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present disclosure will now be described withreference to the following figures in which identical reference numeralsin different figures indicate identical elements, and in which:

FIG. 1 is a perspective view of a prior-art LED signage display;

FIG. 2A is a schematic block diagram of the prior-art digital LEDsignage display shown in FIG. 1 ;

FIG. 2B is a circuit diagram showing a prior-art LED driver of thedigital LED signage display shown in FIG. 1 , driving a plurality ofLEDs;

FIG. 2C is a schematic diagram of another prior-art LED driver of thedigital LED signage display shown in FIG. 1 ;

FIG. 3 is a simplified schematic block diagram of a digital LED signageaccording to an embodiment of this disclosure;

FIG. 4 is a simplified schematic diagram of an advanced LED displaymodule of the digital LED signage shown in FIG. 3 ;

FIGS. 5A and 5B are simplified block diagrams of a LED submodule of theadvanced LED display module shown in FIG. 4 ;

FIG. 6 is a simplified circuit diagram of the power architecture of theLED submodule shown in FIG. 5A;

FIG. 7 is a simplified schematic block diagram of a digital LED signagepowered by solar energy and stored energy according to an alternativeembodiment of this disclosure; and

FIG. 8 is a simplified schematic block diagram of a digital LED signagewith integration of solar energy and energy storage, according to analternative embodiment of this disclosure.

DETAILED DESCRIPTION

The present disclosure generally relates to a LED apparatus. In someembodiments disclosed herein, the LED apparatus may be a digital LEDsignage. The LED apparatus disclosed herein comprises a power andcontrol architecture based on an integrated solution distributed alongthe apparatus. The integrated solution offers a highly efficient andcompact solution for the LED apparatus, and has advantages such ashigher efficiency, compactness, less wiring, simpler heat removal, andno rotational components (i.e., the disclosed LED apparatus isfan-less). The power and control architectures disclosed herein enablethe LED apparatus to achieve improved performance for each individualLED, leading to a highly energy-efficient product.

Turning now to FIG. 3 , an LED apparatus in the form of a digital LEDsignage display is shown and is generally identified using referencenumeral 100. As shown, the digital LED signage display 100 comprises anadvanced LED display module 104 formed by a plurality of LED displaysubmodules 108. Each LED display submodule 108 comprises a plurality ofLEDs 112 drivable at a driving DC voltage such as 5V, 7.5V, 12V, or thelike, depending on the implementation.

The digital LED signage display 100 also comprises a power source orpower supply 102 in the form of an AC/DC power converter in electricalconnection with the LED display submodules 108 of the advanced LEDdisplay module 104, and a gateway 118 in wireless communication with theLED display submodules 108 of the LED display module 104.

The AC/DC power supply 102 may be mounted at a suitable location of thedigital LED signage display 100 such as in a housing thereof and isphysically separated from the advanced LED display module 104. The AC/DCpower supply 102 converts the electrical power of an external AC powersource 110 (such as an AC power grid) into a source DC power at a sourceDC voltage and outputs the source DC power to the LED display submodules108 (and in particular to an LED power Integrated Circuit (IC) chip 142thereof; described in more detail later) via a power cable 106 forpowering the LEDs 112. The source DC voltage is generally higher thanthe driving DC voltage of the LEDs 112. In some embodiments, the sourceDC voltage of the AC/DC power supply 102 is higher than 7.5V. In someembodiments, the source DC voltage of the AC/DC power supply 102 ishigher than 12V. In some embodiments, the source DC voltage of the AC/DCpower supply 102 is about 48V.

The AC/DC power supply 102 outputs a higher source DC voltage comparedto the prior-art, low-voltage power distribution LED signage displays.Therefore, the electrical current passing through the power cable 106and consequently the energy loss on the power cable 106 and heatgenerated therefrom are substantially smaller than that of the prior-artdesigns that have similar constant power consumption. Furthermore, thehigh-voltage distribution (for example, 48V) significantly facilitatesthe integration of solar energy and energy storage (batteries) into thedigital LED signage display 100. In comparison, the prior-art designsrequire multiple power conversion components to implement solar energyand energy storage integration.

Referring again to FIG. 3 , the gateway 118 is configured for wirelesslycommunicating with the LED display submodules 108 (and in particular awireless communication unit 144 thereof shown in FIGS. 5A, 5B anddescribed in more detail later) and with an external computing device114 such as a desktop computer, a laptop computer, a smartphone, atablet, or the like. Therefore, a user (not shown) of the computingdevice 114 may initiate a command for controlling the LED signagedisplay 100 that is sent wirelessly to the gateway 118. In response tothe command, the gateway 118 then wirelessly communicates with the LEDsubmodules 108 to adjust the lighting of the LEDs 112 thereof.

In various embodiments, the wireless connection between the gateway 118and the LED submodules 108 and/or the wireless connection between thegateway 118 and the external computing device 114 may be any suitablewireless communication technologies such as WI-FI®, (WI-FI is aregistered trademark of the City of Atlanta DBA Hartsfield-JacksonAtlanta International Airport Municipal Corp., Atlanta, Ga., USA),BLUETOOTH® (BLUETOOTH is a registered trademark of Bluetooth Sig Inc.,Kirkland, Wash., USA), ZIGBEE® (ZIGBEE is a registered trademark ofZigBee Alliance Corp., San Ramon, Calif., USA), wireless mobiletelecommunications technologies (such as GSM, CDMA, LTE, and the like),and/or the like.

FIG. 4 is a schematic diagram of the advanced LED display module 104. Asdescribed above, the advanced LED display module 104 comprises aplurality of LED submodules 108 wherein the LED submodule 108A at theupper-right corner thereof is shown separated from other LED submodules108 for clearer illustration of submodule. Each LED submodule 108(including submodule 108A) comprises one or more LEDs 112.

In the example shown in FIG. 4 , the advanced LED display module 104comprises twenty four (24) LED submodules 108 arranged as a 4-by-6matrix. Of course, in other embodiments, the LED module 104 may comprisedifferent numbers of LED submodules 108, and the LED submodules 108 maybe arranged in different configurations for example, in differentnumbers of rows and columns and/or in different layouts such astriangles, circles, and the like.

In the example shown in FIG. 4 , each LED submodule 108 preferablycomprises nine (9) LEDs 112 arranged in a 3-by-3 matrix which is optimalfor this example of an integrated solution based on Applicant'spower-loss calculation. However, in other embodiments, an LED submodule108 may comprise different numbers of LEDs 112, and the LEDs 112 may bearranged in different configurations such as in different numbers ofrows and columns, and/or in different layouts such as triangles,circles, and the like.

FIGS. 5A and 5B are simplified block diagrams of an LED submodule 108.As shown, the LED submodule 108 comprises and integrates therein one ormore LEDs 112 and an LED power Integrated Circuit (IC) chip 142 thatprovides a multi-functional, integrated solution for individuallypowering and controlling each LED 112 of the LED submodule 108 (forexample, via an individual power wire and an individual signal wire).The LED power IC 142 may comprise a wireless communication unit 144 suchas a radio frequency (RF) wireless transceiver, a digital control unit146, and a multi-output DC/DC converter 148.

The wireless communication unit 144 is in signal communication with thedigital control unit 146 and is in wireless communication with thegateway 118 for wirelessly receiving the control information such ascolor, light intensity, and the like from the gateway 118 (or a centralcontroller) of the digital signage 100. In this embodiment, the gateway118 is physically separated from the advanced LED display module 104. Inresponse to instructions received from one or more computing devices114, the gateway 118 communicates with the wireless communication unit144 of the LED Power IC 142 of each LED submodule 108 via a wirelesscommunication connection 154 for controlling the corresponding LEDs 112in the LED submodule 108. The wireless communication unit 144 alsoreports the status of each LED 112 in the LED submodule 108 fordiagnosis and troubleshooting purposes. The wireless communication unit144 thus eliminates the need of control-wires required in conventionaldesigns.

The digital control unit 146 provides control signals for themulti-output DC/DC converter 148. It also receives the high-levelsignals from the wireless communication unit 144, then decodes theinformation therein and finally, produces appropriate gate signals forthe digital switches/MOSFETs (similar to the digital switches 34 of FIG.2A) of the multi-output DC/DC converter 148. The digital control units146 play a pivotal role in system optimization, diagnosis, andreliability of the advanced LED display module 104. Each digital controlunit 146 provides substantial flexibility to control LEDs 112 of therespective LED submodule 108 in an optimized manner, updates therequired information through the wireless communication unit 144, andreceives system updates.

FIG. 6 is a simplified circuit diagram of the power architecture of theLED power IC 142, showing the multi-output DC/DC converter 148 of theLED power IC 142 driving the LEDs 112. As shown, the DC/DC converter 148of the LED power IC 142 receives the high-voltage DC power from theAC/DC power supply 102 via the power cable 106, converts thehigh-voltage power to suitable low-voltage DC power such as 5V or 12V DCpower depending on the implementation, and independently outputs thelow-voltage DC power via an electrical wire or conductor 150 to each LED112 of the LED submodule 108. As the DC/DC converter 148 is physicallyin the LED submodule 108, the length of each electrical wire orconductor 150 is much shorter than that of the power cable 106.

With above design, a major portion of the electrical path from the AC/DCpower supply 102 to each LED 112 of the advanced LED display module 104is a high-voltage, small-current path. Subsequently, the energy lossesin the form of heat through the electrical path are significantlyreduced.

Moreover, each multi-output DC/DC converter 148 can independently andprecisely control the LEDs 112 in the respective submodule 108 byindependently and precisely controlling the current of each output 150.As a result, the light intensity of each LED 112 may be smoothlymodulated for smooth dimming. The DC/DC converter 148 altogethereliminates the need for series resistors and drivers to perform dimming.

The control on the voltage across each LED 112 and current therethroughprovides substantial flexibility to optimize the operation of the LEDs112 and offers higher overall efficiency of the digital LED signage 100.In addition, the DC/DC converter 148 is able to smoothly modulate itsoutput currents by ramping up and down the corresponding outputvoltages. On the other hand, the PWM signals and the LED drivers of theprior-art LED signage displays instantaneously apply the low-voltagepower on LEDs, which creates significant amounts of Electro MagneticInterference (EMI) and switching losses. By using a tight closed-loopcontrol on the output currents of each multi-output DC/DC converter 148,the output currents thereof can be smoothly modulated. The EMI issuesand switching losses are thus eliminated or at least significantlyreduced.

In the prior-art design as shown in FIGS. 1 to 2C, one or more powercables 16A are required for electrical connection between the powerconverter 18 and each LED driver 22 of the LED display module 12 forpowering the LEDs 24. One or more control cables 16B, for example, inthe form of ribbon cables, are also required for electrical connectionbetween the central controller 20 and each LED driver 22 of the LEDdisplay module 12 for transmission of control signals.

On the other hand, the digital LED signage 100 disclosed herein onlyrequires a power cable 106 with each wire therein connecting the AC/DCpower supply 102 to a respective LED submodule 108 (in particular, tothe DC/DC converter 148 of the LED power IC 142 of the LED submodule108). The digital LED signage 100 does not require any control wiresbecause the control signals are transmitted to the LED submodule 108wirelessly. Therefore, the digital LED signage 100 and its LEDpower/lighting management comprise a significantly reduced number ofwires thereby reducing the risk of lighting malfunctions caused bybroken wires in the cable 106, reducing the cost of manufacturing fordigital LED signage 100, and simplifying the diagnoses and repairs inthe event that any wires in the cable 106 are broken.

In above embodiments, the digital LED signage 100 comprises an AC/DCpower supply 102. In an alternative embodiment as shown in FIG. 7 , thedigital LED signage 200 may comprise a solar panel 202 having ahigh-voltage DC output such as a 48V DC output and in electricalconnection with an advanced LED display module 104 and an energy-storageunit 204 such as a rechargeable battery pack for powering the advancedLED display module 104 and for charging the energy-storage unit 204. Asthose skilled in the art will appreciate, the energy-storage unit 204may also output a high-voltage DC power to the advanced LED displaymodule 104. Therefore, the combination of the solar panel 202 and theenergy storage unit 204 is equivalent to the power supply 102 shown inFIG. 3 .

FIG. 8 shows a simplified block diagram of a digital LED signage 240according to another embodiment of the present disclosure. The digitalLED signage 240 in this embodiment comprises an advanced LED displaymodule 104 selectively coupled to an AC/DC power supply 102 in the formof an AC/DC power converter electrically connectable to an AC powersource, and a solar panel 202 having an energy storage unit 204 such asa rechargeable battery pack via switches S₁ and S₂. In other words, thepower source of the advanced LED display module 104 is switchablebetween at least the AC/DC converter 102 and a combination of a solarpanel and an energy storage unit via switches S₁ and S₂.

The AC/DC power supply 102 receives AC power from an AC grid 110 andconverts the AC power of the AC grid 110 to a high-voltage DC power suchas a 48V DC power for selectively outputting the DC power to theadvanced LED display module 104 when the switch S₁ is closed and theswitch S₂ is open.

The solar panel 202 has a high-voltage DC power output such as a 48V DCpower output and is in electrical connection with the energy-storageunit 204 for charging the energy-storage unit 204. When the switch S₁ isopen and the switch S₂ is closed, both the solar panel 202 and theenergy-storage unit 204 are electrically connected to the advanced LEDdisplay module 104 for selectively outputting the high-voltage DC powerthereto. Therefore, the power supplied to the advanced LED displaymodule 104 may be switched as needed between the AC grid 110 and thesolar panel 202/energy-storage unit 204. For example, the advanced LEDdisplay module 104 may be powered by the solar panel 202/energy-storageunit 204 when the power output therefrom is sufficient, and may bepowered by the AC grid 110 when the power output from the solar panel202/energy-storage unit 204 is insufficient.

While in above embodiments, the power and control architecture isdescribed for use in digital LED signage, those skilled in the artappreciate that in some alternative embodiments, the power and controlarchitecture may be used in other types of LED devices, such as an LEDlighting device having a plurality of LEDs.

Although in above embodiments, an LED display system having an LEDsignage display is disclosed, in some alternative embodiments, the LEDsignage display may be an LED lighting apparatus, which, rather thanbeing used for displaying images, is used for lighting purposes.Correspondingly, the LED system in these embodiments is then an LEDlighting system.

In above embodiments, the advanced LED display module 104 comprises aplurality of LED submodules 108, and each LED submodule 108 comprises aplurality of LEDs 112. In some embodiments, each LED submodule 108 maycomprise only one LED 112. In some embodiments, the advanced LED displaymodule 104 may comprise only one LED submodule 108.

In above embodiments, each DC/DC convertor 148 is physically integratedinto the respective LED submodule 108. In some embodiments, at leastsome of the DC/DC convertors 148 are physically in proximity with therespective LED submodules 108. For example, in one embodiment, at leastsome of the DC/DC convertors 148 may be removably attached to the backof the respective LED submodules 108.

Although embodiments have been described above with reference to theaccompanying drawings, those of skill in the art will appreciate thatvariations and modifications may be made without departing from thescope thereof as defined by the appended claims.

What is claimed is:
 1. A circuit module physically separated from a power source, for electrically coupling to the power source and powering a plurality of direct-current (DC) lighting components, the power source outputting a source DC power at a source DC voltage, the plurality of DC lighting components drivable by a driving DC power at a driving DC voltage lower than the source DC voltage, the circuit module comprising: one or more circuit submodules, each circuit submodule comprising therein a DC-to-DC (DC/DC) converter for electrically coupling to the power source via one or more cables; the DC/DC converter comprising a plurality of outputs, each of the plurality of outputs electrically coupled to a respective one of the plurality of lighting components for converting the source DC power to the driving DC power at the driving DC voltage and smoothly modulating currents of the plurality of outputs for individually driving the lighting component.
 2. The circuit module of claim 1, wherein the source DC voltage is higher than 12V.
 3. The circuit module of claim 1 further comprising a gateway for wirelessly communicating with a computing device; wherein each circuit submodule further comprises a wireless communication unit configured for wireless communicating with the gateway; and wherein the gateway is configured for wirelessly receiving from the computing device a command and in response wirelessly communicating with the wireless communication unit of each circuit submodule for controlling the lighting of the lighting components coupled thereto.
 4. The circuit module of claim 3, wherein each circuit submodule further comprises a control unit in signal communication with the wireless communication unit and configured for controlling the lighting of lighting components coupled thereto.
 5. The circuit module of claim 1, wherein the DC/DC converter of each LED submodule is configured for using a closed-loop control to smoothly modulate the currents of the plurality of outputs thereof.
 6. The circuit module of claim 1, wherein the DC/DC converter of each circuit submodule is configured for adjusting output voltages thereof to smoothly modulate the output currents thereof.
 7. A lighting apparatus comprising: a plurality of lighting components drivable at a driving DC voltage; and an electrical path for connecting a power source to each lighting component for powering the lighting component by the power source; wherein each electrical path comprises a first portion for receiving from the power source a source DC power at a source DC voltage and a second portion, the second portion comprising a plurality of outputs, each of the plurality of outputs individually connecting to a respective one of the plurality of lighting components at the driving DC voltage; wherein the driving DC voltage is lower than the source DC voltage; wherein the length of the first portion is longer than that of the second portion; and wherein currents of the plurality of outputs are configured for being smoothly modulated.
 8. The lighting apparatus of claim 7, wherein the source voltage is higher than 12V.
 9. The lighting apparatus of claim 7 further comprising: one or more DC/DC convertors coupled to the electrical paths between the first portion and the second portion thereof for converting the source DC voltage to the driving DC voltage and smoothly modulating the currents of the plurality of outputs; wherein each lighting component is individually powered by an output of the one or more DC/DC convertors.
 10. The lighting apparatus of claim 7 further comprising: a gateway for wirelessly communicating with a computing device; and one or more wireless communication units coupled to the plurality of lighting components and configured for wireless communicating with the gateway; wherein the gateway is configured for wirelessly receiving from the computing device a command and in response, wirelessly communicating with the one or more wireless communication units for controlling the lighting of the lighting components.
 11. The lighting apparatus of claim 10 wherein the one or more wireless communication units are coupled to the plurality of lighting components through one or more control units; and wherein the one or more control units are configured for controlling the lighting of the plurality of lighting components in response to the signal received from the one or more wireless communication units.
 12. The lighting apparatus of claim 7 further comprising at least an AC/DC converter for converting an AC power of the power source to the source DC power for inputting to the first portion of each electrical path.
 13. The lighting apparatus of claim 7, wherein the plurality of outputs of the second portion are configured for being controlled by a closed-loop control to smoothly modulate the currents thereof.
 14. The lighting apparatus of claim 7, wherein the currents of the plurality of outputs are configured for being smoothly modulated by adjusting output voltages of the plurality of outputs.
 15. A method of powering a plurality of lighting components drivable at a driving DC voltage, the method comprising: establishing a plurality of electrical paths, each electrical path connecting a power source to one of the plurality of lighting components for powering the one of the plurality of lighting components by the power source; wherein each electrical path comprises a major portion receiving from the power source a source DC power at a source DC voltage higher than the driving DC voltage, and a minor portion, the minor portion comprising a plurality of outputs each individually connecting to a respective one of the plurality of lighting components at the driving DC voltage; and smoothly modulating currents of the plurality of outputs of the minor portions.
 16. The method of claim 15, wherein said establishing the plurality of electrical paths comprises: converting the source DC voltage to the driving DC voltage at locations between the major and minor portions of the plurality of electrical paths by using one or more DC/DC convertors; and individually powering each lighting component by an output of the one or more DC/DC convertors.
 17. The method of claim 15 further comprising: wirelessly commanding the plurality of lighting components for controlling the lighting of the plurality of lighting components.
 18. The method of claim 17, wherein said wirelessly commanding the plurality of lighting components comprises: wirelessly commanding one or more wireless communication units to send control signals to the plurality of lighting components through one or more control units for controlling the lighting of the plurality of lighting components.
 19. The method of claim 18, wherein said wirelessly commanding the plurality of lighting components further comprises: individually controlling the lighting of each of the plurality of lighting components in response to said commanding.
 20. The method of claim 15, wherein said smoothly modulating the currents of the plurality of outputs comprises: using a closed-loop control to smoothly modulate the currents of the plurality of outputs of the minor portions.
 21. The method of claim 15, wherein said smoothly modulating the currents of the plurality of outputs of the minor portions comprises: smoothly modulating the currents of the plurality of outputs of the minor portions by adjusting output voltages of the plurality of outputs. 